Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
1.
Nature ; 555(7695): 223-226, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29516995

RESUMEN

The depth to which Jupiter's observed east-west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno's gravitational measurements have revealed that Jupiter's gravitational field is north-south asymmetric, which is a signature of the planet's atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J8 and J10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter's total mass.

2.
Nature ; 555(7695): 227-230, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29517000

RESUMEN

Jupiter's atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant's interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter's gravity field is north-south asymmetric and the determination of its non-zero odd gravitational harmonics J3, J5, J7 and J9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter's even gravitational harmonics J4, J6, J8 and J10 as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.

3.
Nature ; 555(7695): 220-222, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29517001

RESUMEN

The gravity harmonics of a fluid, rotating planet can be decomposed into static components arising from solid-body rotation and dynamic components arising from flows. In the absence of internal dynamics, the gravity field is axially and hemispherically symmetric and is dominated by even zonal gravity harmonics J2n that are approximately proportional to qn, where q is the ratio between centrifugal acceleration and gravity at the planet's equator. Any asymmetry in the gravity field is attributed to differential rotation and deep atmospheric flows. The odd harmonics, J3, J5, J7, J9 and higher, are a measure of the depth of the winds in the different zones of the atmosphere. Here we report measurements of Jupiter's gravity harmonics (both even and odd) through precise Doppler tracking of the Juno spacecraft in its polar orbit around Jupiter. We find a north-south asymmetry, which is a signature of atmospheric and interior flows. Analysis of the harmonics, described in two accompanying papers, provides the vertical profile of the winds and precise constraints for the depth of Jupiter's dynamical atmosphere.

4.
Science ; 364(6445)2019 06 14.
Artículo en Inglés | MEDLINE | ID: mdl-30655447

RESUMEN

The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with Earth was monitored to determine the gravitational field of the planet and the mass of its rings. We find that Saturn's gravity deviates from theoretical expectations and requires differential rotation of the atmosphere extending to a depth of at least 9000 kilometers. The total mass of the rings is (1.54 ± 0.49) × 1019 kilograms (0.41 ± 0.13 times that of the moon Mimas), indicating that the rings may have formed 107 to 108 years ago.

5.
Science ; 356(6340): 821-825, 2017 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-28546206

RESUMEN

On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter's poles show a chaotic scene, unlike Saturn's poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth's Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno's measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter's core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content.

6.
Arch Pathol Lab Med ; 103(9): 479-82, 1979 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-582380

RESUMEN

Clinicopathologic studies of four patients with juvenile diabetes mellitus and renal disease demonstrated the pathogenetic variability of nephropathy in diabetic patients. Only in one patient was the clinical nephropathy associated with the typical diabetic glomerulosclerosis. Another patient had steroid responsive nephrotic syndrome superimposed on minimal diabetic glomerulosclerosis. A third patient had steroid resistant nephrotic syndrome associated with mild diabetic glomerulosclerosis and with later appearance of Grave's disease. The fourth patient, in addition to moderate diabetic glomerulosclerosis had prominent tubulointerstitial nephritis, the latter probably being responsible for the rapidly declining renal function. The poor prognosis associated with diabetic nephropathy warrants a careful search for other potentially treatable causes of nephropathy in patients with juvenile diabetes mellitus.


Asunto(s)
Diabetes Mellitus Tipo 1/patología , Nefropatías Diabéticas/patología , Riñón/patología , Adolescente , Adulto , Membrana Basal/patología , Niño , Diabetes Mellitus Tipo 1/fisiopatología , Nefropatías Diabéticas/fisiopatología , Femenino , Tasa de Filtración Glomerular , Humanos , Inmunoglobulinas , Glomérulos Renales/patología , Túbulos Renales/patología , Masculino , Síndrome Nefrótico/etiología , Síndrome Nefrótico/patología , Factores de Tiempo
9.
Bioelectromagnetics ; 26(2): 145-52, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15672368

RESUMEN

A study of the influence of electromagnetic fields (EMF) of various frequencies, from 50 up to 400 Hz, on the catalytic activity of soluble and insoluble horseradish peroxidase (POD) was carried out. To simulate the conditions in which the enzyme operates in vivo, the POD was immobilized by entrapment on a gelatin membrane or by covalent attachment on a nylon graft membrane. The rate of inactivation of the soluble POD was found to exhibit positive and negative interactions with the 1 mT applied magnetic field, with an optimum positive effect at 130 Hz. The immobilized PODs, on the contrary, do not exhibit negative interactions, but show a maximum positive interaction at 150 Hz when entrapped and at 170 Hz when covalently attached. At 50 Hz and at frequencies higher than 250 Hz no effects were observed with insoluble POD. The optimum frequency of positive interaction between the EMF and the catalytic activity of the insoluble enzymes is shifted with respect to that of the soluble enzymes towards higher frequencies, the size of the shifts being dependent on the intensity of the physical forces involved in the immobilization process.


Asunto(s)
Electricidad , Campos Electromagnéticos , Peroxidasa de Rábano Silvestre/química , Peroxidasa de Rábano Silvestre/efectos de la radiación , Catálisis/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Activación Enzimática/efectos de la radiación , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/efectos de la radiación , Dosis de Radiación
10.
J Pediatr ; 89(6): 978-81, 1976 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-993927

RESUMEN

Attention is called to a poorly recognized syndrome of neonatal renal arterial embolism, presumably from the ductus arteriosum, resulting in malignant hypertension, congestive heart failure, respiratory distress, and increased renin secretion. Radiographic studies revealed a ductus diverticulum and multiple narrowed arteries including the lower pole branches of the right renal artery. Renal scan showed poor imaging of the lower pole of the right kidney. Nephrectomy resulted in a prompt return of the blood pressure into the normal range. Eight cases recorded in the literature resemble the one reported here, and six of the eight had an associated thrombosis of the ductus arteriosum. Our patient appears to be the first case recognized by modern techniques followed by nephrectomy and clinical cure.


Asunto(s)
Embolia/complicaciones , Enfermedades del Recién Nacido/complicaciones , Obstrucción de la Arteria Renal/complicaciones , Aortografía , Conducto Arterial/diagnóstico por imagen , Insuficiencia Cardíaca/etiología , Humanos , Hipertensión Maligna/etiología , Recién Nacido , Masculino , Nefrectomía , Cintigrafía , Renina/sangre , Síndrome de Dificultad Respiratoria del Recién Nacido/etiología , Síndrome
11.
Scand J Immunol ; 6(3): 195-202, 1977.
Artículo en Inglés | MEDLINE | ID: mdl-847401

RESUMEN

A novel immunoadsorbent is described in which soluble canine glomerular basement membrane (GBM) antigen was immobilized in collodion membranes adherent to small charcoal particles. As much as 80% of the added GBM antigen was retained in the collodion-charcoal. The binding of GBM antibody to immobilized GBM antigen in vitro and in vivo was demonstrated. For in vivo studies, an extracorporeal circulation system was established, and mongrel dogs were then injected intravenously with GBM collodion-charcoal for 4 h. Renal tissue was examined by fluorescence and light microscopy for the deposition of heterologous gamma globulin and glomerular inflammation before and after the extracorporeal procedure. Results showed less deposition of heterologous IgG and less inflammation in experimental dog kidneys than in control kidneys. There was no evidence of release of 131I-labeled GBM from the immunoadsorbent at the conclusion of perfusion experiments and no significant biochemical or hematologic alterations. Finally, extracorporeal immunoadsorbent treatment was capable of attenuating the early heterologous phase of passive canine nephrotoxic nephritis and may have a potential role in the therapy of anti-GBM-mediated nephropathy.


Asunto(s)
Complejo Antígeno-Anticuerpo/uso terapéutico , Glomerulonefritis/inmunología , Inmunoadsorbentes/uso terapéutico , Glomérulos Renales/inmunología , Animales , Anticuerpos , Membrana Basal/inmunología , Sitios de Unión de Anticuerpos/efectos de los fármacos , Inhibición de Migración Celular , Perros , Circulación Extracorporea , Glomerulonefritis/patología , Glomerulonefritis/terapia , Inmunidad Celular/efectos de los fármacos , Inmunización , Marcaje Isotópico , Riñón/patología , Riñón/fisiología , Conejos
12.
J Rheumatol ; 4(4): 358-68, 1977.
Artículo en Inglés | MEDLINE | ID: mdl-604475

RESUMEN

Fifty-three renal specimens from 48 patients with SLE were examined for the presence of RTE in the glomeruli. Glomerular RTE, presumably in immune complex form was detected in 60% of the tissues. The deposition of these complexes was related to the severity of histologic changes and activity of SLE. In addition, glomerular localization of RTE was associated with decreased renal function and increased proteinuria. The association between the presence of glomerular RTE antigen, the severity of renal histologic changes and the decreased renal function suggested a possible role for this antigen in the pathogenesis of lupus nephritis.


Asunto(s)
Complejo Antígeno-Anticuerpo , Glomérulos Renales/inmunología , Túbulos Renales Proximales/inmunología , Lupus Eritematoso Sistémico/inmunología , Nefritis/inmunología , Adolescente , Adulto , Niño , Femenino , Humanos , Riñón/metabolismo , Glomérulos Renales/patología , Túbulos Renales Proximales/patología , Lupus Eritematoso Sistémico/metabolismo , Lupus Eritematoso Sistémico/patología , Masculino , Persona de Mediana Edad , Nefritis/metabolismo , Nefritis/patología
13.
Nephron ; 24(5): 223-31, 1979.
Artículo en Inglés | MEDLINE | ID: mdl-503263

RESUMEN

2 patients developed the nephrotic syndrome several years after diagnoses of chronic lymphocytic leukemia. In both cases light microscopy showed membranoproliferative glomerulonephritis. Electron microscopy and immunofluorescent staining revealed electron-dense deposits and deposition of immunoglobulins and C3. Both patients had single-component IgG cryoglobulinemia. The eluted glomerular-bound protein contained IgG only. IgG in patients' sera, cryoglobulins, and kidney eluate had kappa light chains only. Immune complexes were detected in the sera and in the cryoglobulins by the Clq binding test. Immunoadsorption studies revealed anti-IgG antibodies in the patients' sera, cryoglobulin, and kidney eluate. Direct immunofluorescent studies using the patients' sera, cryoglobulins, and kidney eluate on frozen sections of patients' kidneys were positive, providing additional evidence for the immune complex nature of the glomerulonephritis. The immunohistochemical studies of our patients are suggestive of the presence of circulating IgG-anti-IgG immune complexes and their possible involvement in the pathogenesis of the glomerulonephritis and the nephrotic syndrome in these 2 cases.


Asunto(s)
Complejo Antígeno-Anticuerpo , Crioglobulinas , Glomerulonefritis/inmunología , Inmunoglobulina G , Leucemia Linfoide/complicaciones , Síndrome Nefrótico/inmunología , Paraproteinemias/complicaciones , Complemento C1/metabolismo , Complemento C3 , Femenino , Glomerulonefritis/patología , Humanos , Glomérulos Renales/patología , Masculino , Persona de Mediana Edad , Paraproteinemias/inmunología
14.
Am J Kidney Dis ; 9(2): 108-14, 1987 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-3826059

RESUMEN

The long-term clinical course of 60 children with steroid-responsive nephrotic syndrome, observed for a minimum of 10 years from onset, was studied (mean 14.5 +/- 0.5 years). Four children had only a single episode, seven children experienced only one to three relapses early in their course, and the remaining 49 patients (82%) experienced frequently relapsing steroid-dependent disease. Nearly half of these (47%) continued to relapse into their late teens and early twenties. All 20 children treated with cyclophosphamide because of steroid-induced side effects developed complete remissions of the nephrotic syndrome. These were sustained in 70% for 9.1 +/- 0.6 years, with a reduction of disease severity in the remaining 30%. In contrast, only 48% of patients treated with prednisone alone were in remission at last follow-up (P = .06). Ten of the children treated with cyclophosphamide had the minimal change lesion prior to therapy; 90% of these had permanent remissions. Only 50% of the six children with focal glomerulosclerosis and four children with mesangial proliferation have had permanent remissions. None of the patients developed renal insufficiency. Children treated with prednisone alone were -0.93 +/- 0.3 SD below the mean for height at last follow-up. Cyclophosphamide treatment was associated with an increase in height SD scores from -0.84 +/- 0.4 to -0.28 +/- 0.3. Children with severe growth impairment demonstrated dramatic catch-up growth when treated with cyclophosphamide with SD scores increasing from -2.29 +/- 0.8 to -0.43 +/- 0.6 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Estatura , Ciclofosfamida/uso terapéutico , Riñón/patología , Síndrome Nefrótico/diagnóstico , Adolescente , Niño , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Lactante , Masculino , Síndrome Nefrótico/tratamiento farmacológico , Síndrome Nefrótico/fisiopatología , Prednisona/uso terapéutico , Factores de Tiempo
15.
Bioelectromagnetics ; 24(7): 449-56, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12955749

RESUMEN

The influence of an extremely low frequency (ELF) magnetic field (50 Hz and 1 mT, EMF) on the activity of a soluble and insoluble horseradish peroxidase (E.C. 1.11.17) has been studied as a function of time. Insoluble derivatives were obtained by enzyme entrapment into two different gelatin membranes or by covalent attachment of the enzyme on two nylon membranes, differently preactivated. Results have shown that the field affects the inactivation rate of the soluble enzyme, while no effects are observed with insoluble derivatives. Since in vivo enzymes are immobilised into the biomembrane bilayer or entrapped into the cytoplasmic mixture, one might speculate that our experimental conditions do not reflect the catalytic activity of the enzymes in vivo.


Asunto(s)
Campos Electromagnéticos , Activación Enzimática/efectos de la radiación , Enzimas Inmovilizadas/efectos de la radiación , Peroxidasa de Rábano Silvestre/química , Peroxidasa de Rábano Silvestre/efectos de la radiación , Membranas Artificiales , Benzotiazoles , Relación Dosis-Respuesta en la Radiación , Estabilidad de Enzimas/efectos de la radiación , Peróxido de Hidrógeno/química , Ondas de Radio , Solubilidad , Soluciones , Ácidos Sulfónicos/química
16.
Pediatr Nephrol ; 2(2): 244-6, 1988 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-3153018

RESUMEN

Children with the idiopathic nephrotic syndrome (NS) are known to be susceptible to bacterial infections. A recent report suggested that splenic hypofunction may be responsible for this immunological defect. We assessed splenic function by counting the circulating pocked red blood cells (PkRBCs) using interference phase contrast microscopy. PkRBCs are removed by the spleen, so that normal eusplenic individuals have less than 2% PkRBCs while asplenics have 15%-30%. Intermediate values are seen in hyposplenism. Thirty-three measurements of PkRBCs were made in 19 children with NS (mean age 7.5 +/- 0.8 years). PkRBCs were normal in all children tested (range 0-0.8%), including two patients with bacterial peritonitis associated with relapse. Thus we were unable to find evidence of hyposplenism in children with NS.


Asunto(s)
Síndrome Nefrótico/fisiopatología , Bazo/fisiopatología , Adolescente , Adulto , Infecciones Bacterianas/etiología , Niño , Preescolar , Eritrocitos/patología , Humanos , Lactante , Síndrome Nefrótico/complicaciones , Síndrome Nefrótico/inmunología , Bazo/inmunología , Bazo/patología
17.
J Neurooncol ; 41(1): 71-5, 1999 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-10222425

RESUMEN

We report a giant pituitary adenoma with aggressive histologic features that prominently invaded the nasopharynx. Magnetic resonance imaging (MRI) demonstrated a large heterogeneous nodular mass that was hypointense to isointense on T1-weighted images and mixed hypointense, isointense, and hyperintense on T2-weighted images. The mass measured 7.5 x 5 x 7 cm, extending from the nasopharynx posteriorly through the clivus, and superiorly through the paranasal sinuses, and sellar-suprasellar region. After contrast administration, heterogeneous nodular enhancement was noted. A nasopharyngeal neoplasm extending into the sella was suspected because voice change and nasal speech long preceded the patient's visual symptoms. A biopsy disclosed an aggressive, infiltrating, hemorrhagic tumor, which was diagnosed as a non-secreting pituitary macroadenoma. This report indicates that pituitary adenomas may grow invasively to tremendously large sizes resulting in their initial presentation as nasopharyngeal masses.


Asunto(s)
Adenoma/diagnóstico , Neoplasias Nasofaríngeas/diagnóstico , Neoplasias Hipofisarias/diagnóstico , Adenoma/metabolismo , Adenoma/patología , Anciano , Diagnóstico Diferencial , Humanos , Imagen por Resonancia Magnética , Masculino , Neoplasias Hipofisarias/metabolismo , Neoplasias Hipofisarias/patología , Prolactina/sangre , Hormona Liberadora de Tirotropina/sangre
18.
Biotechnol Bioeng ; 79(3): 334-46, 2002 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-12115422

RESUMEN

A new hydrophobic and catalytic membrane was prepared by immobilizing Penicillin G acylase (PGA, EC.3.5.1.11) from E. coli on a nylon membrane, chemically grafted with butylmethacrylate (BMA). Hexamethylenediamine (HMDA) and glutaraldehyde (Glu) were used as a spacer and coupling agent, respectively. PGA was used for the enzymatic synthesis of cephalexin, using D(-)-phenylglycine methyl ester (PGME) and 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) as substrates. Several factors affecting this reaction, such as pH, temperature, and concentrations of substrates were investigated. The results indicated good enzyme-binding efficiency of the pre-treated membrane, and an increased stability of the immobilized PGA towards pH and temperature. Calculation of the activation energies showed that cephalexin production by the immobilized biocatalyst was limited by diffusion, resulting in a decrease of enzyme activity and substrate affinity. Temperature gradients were employed as a way to reduce the effects of diffusion limitation. Cephalexin was found to linearly increase with the applied temperature gradient. A temperature difference of about 3 degrees C across the catalytic membrane resulted into a cephalexin synthesis increase of 100% with a 50% reduction of the production times. The advantage of using non-isothermal bioreactors in biotechnological processes, including pharmaceutical applications, is also discussed.


Asunto(s)
Antibacterianos/síntesis química , Reactores Biológicos , Cefalexina/síntesis química , Membranas Artificiales , Nylons , Penicilina Amidasa/química , Catálisis , Cefalosporinas/química , Materiales Biocompatibles Revestidos , Enzimas Inmovilizadas , Diseño de Equipo , Escherichia coli/enzimología , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Metacrilatos , Modelos Químicos , Glicoles de Propileno/química , Sensibilidad y Especificidad , Temperatura
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA